1. Field of the Invention
This invention relates to cameras and particularly to an electromagnetic release device arranged with a single electromagnet to perform a number of control functions within a camera.
2. Description of the Prior Art
Generally, a single-lens reflex camera is arranged to form an image of an object to be photographed on a viewfinder and to perform the following sequence of actions. A shutter release operation causes operation of an automatic diaphragm aperture adjusting device, and at the same time, a movable mirror is lifted up to retract it from the photo-taking optical path. Following that, a shutter is operated. After completion of an exposure, the movable mirror goes back to its original position and a winding lock member which has inhibited winding of the film is unlocked to allow the next photographic operation.
Various concepts for controlling this sequence of actions electronically have been introduced of late. For example, some central control arrangements with microcomputers have been proposed to electrically control the above stated series of actions using a magnet for each of the systems including a mirror drive system, an automatic aperture adjusting system, and a shutter system. The central control arrangement with a microcomputer dispenses with mechanical arrangement for signal transfer between one functional system and another (mechanical interlocking relation). Among other advantages, this permits simplification of structural arrangement and adjustment work because each of the series of actions can be performed at times independently of another.
However, such electrical control necessitates temporary conversion of an electrical signal into a mechanical signal for actuating the shutter, the mirror, the film winding lock member, etc. This requires use of many electromagnetic mechanisms and not only complicates the internal construction of the camera but also results in an increase of space needed. The electrical control arrangement of the prior art, therefore, not only hinders efforts to reduce the size of the camera but also is disadvantageous in terms of cost.